Cytoskeleton

Question 1

Cytoskeleton

Answer 1

Network of protein filaments placed in the cytoplasm

Question 2

Function of cytoskeleton

Answer 2

Allows cell to change its shape, move organelles & move from place to place

Question 3

Intermediate filaments

Answer 3

Rope-like fibrous proteins
Least dynamic
10nm in diameter

Question 4

Function of intermediate filaments

Answer 4

Provide cell shape & structural reinforcement
Anchor organelles
Keep nucleus in place

Question 5

Actin filaments

Answer 5

Made of globular protein actin
7nm in diameter
ATP dependent, filament is polar, dynamic instability

Question 6

Molecular motors of actin filaments

Answer 6

Myosin I & II

Question 7

Function of actin filaments

Answer 7

Structural
Movement (amoeboid, muscle)
Mitosis (contractile ring)

Question 8

Microtubules

Answer 8

Tubes of globular protein tubulin
25nm in diameter
GTP dependent, polar, dynamic instability

Question 9

Microtubule organising centers

Answer 9

Centrosome
Mitotic spindle
Basal body

Question 10

Function of microtubules

Answer 10

Maintain cell shape
Anchor organelles
Movement (ciliar, flagellar, intracellular)
Mitosis ( mitotic spindle)

Question 11

The principle of mvement

Answer 11

Transformation of chemical energy into mechanical

Question 12

Molecular motor is composed of

Answer 12

Motor (head) domain

Tail (stalk) domain

Question 13

Motors associated with microtubules

Answer 13

Dynein

Kinesin

Question 14

Types of motor movement

Answer 14

Cytoskeletal structure is fixed
Sliding
Motor is fixed

Question 15

Cytoskeletal structure is fixed

Answer 15

Head binds to cytoskeletal structure that is fixed
Hydrolysis of ATP
Head change conformation & move along cytoskeletal structure
Cargo moves with motor

Question 16

Sliding

Answer 16

Motor is fixed with stalk to one cytoskeletal structure while head contacts other cytoskeletal structure
Cause sliding

Question 17

Intracellular transport

Answer 17

Transport of secretory vesicle by molecular motors (D,K) along MT highway

Question 18

Centriole

Answer 18

Made of MT
Duplicate during S phase
Migrate to opposite poles of cell
Form organizing centers for mitotic spindles

Question 19

Flagella & Cilia structure

Answer 19

Basal body
Axoneme (MT & radial spokes)
Dynein

Question 20

Principle of flagellar & ciliar movement

Answer 20

Stalk of D is fixed to A subunit of MT doublet
Head of D contact B subunit of neighboring MT doublet causing hydrolysis of ATP
Activated head changes its conformation

Question 21

Why do MT doublets in ciliary & flagelllar movement flex?

Answer 21

Because the MT doublets are fixed by radial spokes

Question 22

Function of flagellar & cilliary movement

Answer 22

Move things along surface of cell that lines lumen

Used in locomotion (sperm cell)

Question 23

Bacterial flagellum Composition

Answer 23

Filament composed of flagellin
Hook outside outer membrane
Basal body rings

Question 24

Types of bacteria based on flagellum

Answer 24

Monotrichous
Lophotrichous
Amphitrichous
Peritrichous

Question 25

Amoeboid movement principle

Answer 25

Movement is based on changing shape of cell by forming false feet (pseudopods)

Question 26

Amoeboid movement

Answer 26

Protrusion of pseudopodium Pseudopodium is attached Rest of the cell body is pulled

Question 27

Muscle contraction

Answer 27

1) AP transmits signal down axon 2) AP activates V-gated Ca, Ca rush in 3) Ca cause vesicles to release acetylcholine into synaptic cleft 4) opening of Na/K channel 5) AP spreads through muscle fiber's network of T tubules 6) Depolarization activates V-gated Ca channel that interact with Ca-release channels of SR to activate them & release Ca 7) Ca binds to troponin C that modulates tropomyosin that moves 8) Myosin binds, pulls Z-disk towards each other & shortens sarcomere

Question 28

Muscle relaxation

Answer 28

After no signal, Ca is pumped to Sr by Ca pump | Tropomyosin changes conformation back to its previous state to block binding sites of actin

Question 29

Prophase

Answer 29

Mitotic spindle is formed

Question 30

Centrosome

Answer 30

Organizing centrum for MT | Duplicated in S phase

Question 31

Prometaphase

Answer 31

K MT attach to each sister chromatid at the kinetochore

Question 32

Metaphase

Answer 32

Chromosomes line up on the equator of the cell by polymeration & depolymeration of K MT

Question 33

Anaphase

Answer 33

Dynein pulls chromatids to opposite poles | P MT slide (with help of Kinesin)

Question 34

Telophase

Answer 34

K MT disappear | P MT still polymerate

Question 35

Cytokinesis (Animal Cell)

Answer 35

Process = cleavage Contractile ring is formed Actin filaments slide (by help of myosin II)

Question 36

Cytokinesis (Plant Cell)

Answer 36

Vesicles from GA move along MT to equator of cell & fuse | Produce cell plate

Question 37

Bacterial flagellum composition

Answer 37

Filament flagellin Hook Basal body rings

Question 38

Bacterial flagellum principles

Answer 38

Flow of protons Rotates independently Thick 6 hollow (addition of flagellin subunits at tip)

Question 39

Archaeal flagellum principle

Answer 39

Powered by ATP Rotate as a single flagellum Addition of subunits to base